Sarah Michelle Gellar Rocks Backless Dress, Admits to Wearing Spanx

Sarah Michelle Gellar looked like a knockout at The CW, CBS and Showtime's Summer TCA Party in L.A. on Monday, July 30. Wearing a backless Izmaylova dress with peplum detail, the 36-year-old actress smoldered while posing for photographers at the star-studded event. What pictures didn't show, however, was what the married mother of two was wearing underneath her flirty frock.

The actress -- mom to daughter Charlotte, 3, and son Rocky, 10 months, with husband Freddie Prinze Jr., 37 -- said she stays in shape by "chasing two children all day long." As Gellar explained, "I take advantage of being in California: 'Let's go outside! Let's do this!'"

In her new half-hour comedy The Crazy Ones, Gellar plays a level-headed advertising executive who works for her zany father's (Robin Williams) company. "Being able to have Robin sort of take the lead, for me it's the best of both worlds," said the star, who previously played twins on The CW's Ringer. "I get to spend time with my family and I get to do a job that I love."

Working with Williams has been a dream come true for the Buffy the Vampire Slayer veteran. "He understands the dilemma that I find being caught between my home life and my professional life. He couldn't be more caring," Gellar said of Williams, 62. "My joke is that I actually didn't apply to be on the show -- I actually applied for Robin to adopt me. I didn't realize it was actually a job on a TV show, but since that was second best, I took it!"

To get into character, Gellar said that she draws inspiration from Prinze's interactions with Charlotte. "I'm fortunate enough to get to watch the relationship between my husband and our daughter," she told Us. "I also get to watch the amazing relationship between Robin and Zelda and take from that." (Among his three kids, Williams shares daughter Zelda, 24, with second ex-wife Marsha Garces.)